<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    const message = 'my name is why, why age is 18'
    console.log(message.replace('why', 'kobe')) // my name is kobe, why age is 18
    console.log(message.replaceAll('why', 'kobe')) // my name is kobe, kobe age is 18
  </script>
</body>

</html>